Radio apparatus



Sept. 14, 1943.

E. F. MCDONALD, JR 2,329,634

RADIO [APPARATUS Original Filed Oct. 6, 1959 4 Sheets-Sheet 1 INVENTOR EUGENE Mcfio/vAL-gJk My ATTORN EYS p 1943- E. F. MCDONALD, JR 2,329,634

RADIO APPARATUS Original Filed Oct. 6, 1939 4 Sheets-Sheet 2 INV ENTOR EUGENE F. Mc DONALD, JR.

BY 41% a M ATTORNEYS p 1943 E. F. M DONALD, JR 2,329,634

RADIO APPARATUS Original Filed Oct. 6, 1939 4 Sheets-Sheet I5 INVENTOR fueEn/E li/Vc. Dom/.0 J72 ATTORNEYS septa 1943- E. F. M DONALD, JR 2,329,634

RADIO APPARATUS ori inal Filed Oct. 6, 1959 4 Sheets-Sheet 4 lNV ENTOR EUGENE MCDONALDX J MYM ATTORNEYS Patented Sept. 14, 1943 U PATENT ,OFFICE RADIO-APPARATUS EugeneFrlldcDonald, .ln tchicago, 111. Original application Qctober 6, 1939, Serial No. 298302, now Patent No. 2,250,387, dated July 22,;194 1. Divided and this application April 25, 1941,;Serial'No. 390,405 I' t ac ai (01. 250-33) This invention relates to radio apparatusfand' more particularly to a smalldight weight antenna and the combination thereof with a radio set. 1 i

The invention is particularly useful in connection with portable radio receiving sets havin self-contained batteries associated therewith, al-

though the invention is applicable to-sets operated from power lines. Many such sets have built-in antennae, and When-positioned within shielding structures such as railroad cars, metal" boats, automobiles, airplanes; or even certain types of buildings, in'sufiicient signal energy reaches the antenna'forsatisfactory' operation of theset. In my Patent No. 2,164,251, granted June 27, 1939, and entitled Portable radio re- 1 shielding structure. The present application constitutesan improvement over the -'structure claimed in said patenta-nd also over the structure of my copending application Serial No.

281,297, filed June 26,1939, now Patent No. 2,200,- n

674 granted apparatus. a I 1 'The present invention relates particularly to a small light weight antenna structurewhich may May 14, 1940, and entitled f Radio be connectedto a radio set and positioned in an P opening in a shielding structure so asto markedly reduce impairment of vision'throughsuch opening. The antenna structure formingpart of the present invention is preferably constructed largely .oi transparent materi'als or is of such sizeand configuration that an extremely small area of -the opening is obstructed. For employment'with portable radios the cases of such radios are pref- .erably provided with a compartment for holding the antenna structure and for enabling the same to be removed from the case and supported apart from the set while connected thereto. The antenna .is preferably provided with a flex-ible'con- .nector and also with attaohing devices for enabling the antenna to be detachably secured-to:

a surface ,in any one of a plurality-of positions apart from the set; For permanent installation, the antenna structure maybe permanently secured to such surface by adhesives orotherw-ise,

or the supporting structure into which the -wires constituting the antenna are incorporated may be extended to itself form a closure foran opening in a shielding structure, for ex'amplethe glass of automobile or. other window. --'In such adapted to be positioned in an opening in a shielding structure without, materially obstructingsaid opening. I

* "Another object of the invention is to provide a rigid loop antenna structure including transparent material so as to provide for the passage of light through a major portion thereof.

Another object of the invention is to provide a radioset with an auxiliary antenna capable of being positioned in an opening in ashielding structure without materially obstructing said opening 50 as to enhance radio reception by a set positioned within such shieldingstructure;

Another object of the invention is to providea radio set with both anauxiliary movable antenna and a built-in antenna" so that connection of the auxiliary antenna to *the set disconnects thebuilt-in-antenna. 5 7 v I A further object of the-invention is to provide a radio set with a compartment for receiving'a small light weight antenna so that the antenna may be removed from -the set and positioned apart therefrom for enhancing'reception of radio signals. r 7

A still further object ;-of the invention is to provide a loop antenna in'which the conductors forming theloop are secured to or incorporated into a transparent panel-to form a rigid antenna structure which does not materially obstruct vision therethrough.

Other objects and advantages wil1 appearin'the following description of the {oreferred embodiments shown in the attached drawings, of which:

' '-Figure 1 is an elevation of an antenna'structure in accordance with the present invention;

Figure 2 is a sectional View taken on the line 2-2 of-Figure -1;

Figure 3 "is a fragmentary section on a larger on the line 4-4 of Figure 1;

Figure 7 is a. sectional view taken on the line aft- 1 of'Figure 5 with the attaching means Iomit- Figure 8 is a similar .view of a modified antenna structure;

".Figure 9 is an elevation of another modified .antenna structure; V, .Figure 10 is .a yiew similar to Figure 1 showpermanent installation, it is preferred to provide" :light tweisht; antenna structure particularly-z ing a modified antenna structure adhesively seicuredtozasupporting surface; Y

Figures 11 to 15' inclusive are views similar 'A-tmFigure .7 showing still further modified an- -tenna structures H 60" a shaving .an antennacoil incorporated therein;

Figure 16 is an elevation of a windowpane of the invention 7 Figure 17 is a side elevation of a radio set showing a" compartment foran antenna'in the end of the set casing-with the door'removed'; and Figure 18 is a fragmentary vertical section of the structure of Figure 17 showing the compartment with the antenna structure in dotted lines.-

Referring to the drawings, and more'particw larly to Figures 1 to 4, It indicates, in general, I

an antenna, structure in accordance. with the 10 present invention. The antenna structure .IO

may include a pair of thin transparent plate":

transmitter with respect to the opening. It has j also. been found that "riositionirig'jonly i .a portion of thea'ntenna withinthe opening so that the remainder of the antenna is positioned back of the shielding structure surrounding the opening, many times increases reception over that b- 'ta;ined' when the entire antenna structure is :w'ithinl'the opening.

, It is natural to think that a loop antenna constructedin'accordance with my invention oper- 1 ates 'most satisfactorily when positioned farthest from'the shielding structure, that is, when it is positioned centrally with respect to the opening in-theshielding structure. It has, however, actually been foundthat such is not the case, but

i that when sucha-loopantenna-is positioned cenbe provided with devices such as suction cups I l, and I5 for quickly attachably and adjustably securing the antenna structure to a surface.

such as, for examplathe glass of a window. As shown in Figure 3, the suction cups I4 and [5 are preferably hinged to oneend of the antenna structure by means of hinges I! having one leaf 18 extending between the panels I I and I2 and the other end i9 secured to a suction cup, for example by means ,of a screw threaded stud 20 extending through a threaded aperture 21 the leaf 19. The leaf l8 of the hinge I'I may be secured between the plates H and 12 by any suitable means, for example, rivets, 22. An aperture 23 through the plates -H and i2 and the leaf l8 of the hinge I! may be provided for receiving the stud 20 when the hinge is in the position shown inFigures 3 and 4. The suction cup I6 is preferably pivotally securedto 1a linkid, which is in turn pivotally attached to the plates l I and [Z by means of a bracket 25 I secured to the plates II and. I2, for example by rivets 2E. The rivets 2| and 26 ;further constitute means for securing the plates I I and [2' iii are opaque and render a portion of the aerial structure In opaque, a window portion 21 is provided in the center of the antenna structure. Thus, when the antenna structureis positioned in an opening, for example by attaching the same to a window. glass, vision is permitted through the center of the antenna structure as well as around the edges thereof. The entire structure may be made small in size, fonexample, a structure approximatelyQ x 6%, inches, containing 27 turns, of wire and providing a window portion approximately 6 x 3%, inches has been found to givesatisfactory radio reception. Such a. structure occupies only a small portion of the usual window found in shielding structures. Furthermore, 'the attachingmeans illustrated enables the antenna structure to be positioned .parallel to the plane. of the opening or at any desired angle thereto. In many cases a position at an angle to the :plane of the opening provides satisfactory receptionfand in such cases even a smaller portion of, the opening is obstructed. In most instances it is found'that positioning the aerial structure inl'a' corner of the opening will provide most effective :recepceptionwill depend upon thev direction of the tion. The corner of the opening giwng bestre- H trally of the opening, a minimum of radio energy is received. Although the reason for this unexpected effect is not clearly understood, itis believed tobe caused by, the induction of a voltage in the loopbycurrents induced in the shielding structure, which forms a short circuited turn .around the opening, and the two voltages induced in the.loop, one from currents in the shielding structure and the other by direct induction from received radiation, .are of such phase as to cancel almost entirely, When'the loopis positioned oif center, with respect to the opening, muchmore voltage is induced in the loop than when it ispositioned'centrally, and it is believed that such off center positioning is effectiveto cause the two induced voltages in the loop to be less completely out or phase, with the tenna of my invention, bepositioned 01f center with respect to the center, of an opening in a shielding structure; near which the loop is placed.

It has also been; foundimportant to maintain the connecting wires leading from the antenna structure to the set in spaced apart position. An effective means for accomplishing this is to stitch theconnecting-wiresjfi and 29 to: the edges of a strip 30 of relatively stiff fabric. The fabric strip 30 is preferably secured to theantenna structure, for example, by. inserting the ,end of the strip between ,plates II, and I2 and. riveting the sameto the plates bymeans ,of a;rivet 3|. Such structure preventsstrain-from being appliedto theconductors 23 and and, asbefore mentioned, also maintains the. conductors in spaced apart position. The strip 30 and conductors 28 and 'lljconstitute a flexible connection which, as shown in Figure 17, may terminate at ,itsother end in ,a conventional'plug 32 whichis adapted to .be received in a jack 33 as hereinafter more fully described.

A modified type of antenna is shown in Figure 5 which obstructs vision in a less degree than the antenna of Figures 1 and 2. yThe antenna structureof Flgure-5 may be generally similar to that of Figure 1. Instead of employing a link to attach the vacuum cup 34 to the transparent plates 35 and 36, a yoke 3'! is pivoted to brackets 38 which may have portions 39 extending be- ,tween-thetransparent plates '35 and 36 and riveted thereto. The vacuum cup '34; may be attached to the yoke by means of a hinge lflso that the antenna 1' structure may-be 'detachably secured. to a surface in any-zone of a plurality of angular positions with respect thereto as well as yparalleli to-theplane. of the surface. It will be noted that the window portions 4| of the trans- :parentpl'ates 35 and 36 aresubstantially. unobstructed. and: that .there r is; even less obstruction to vision through the antenna structure than is the case with the structure of Figure l.

Instead'of depending upon an adhesive to hold the coil 42 in position between the plates and 36, a third plate 43 of transparent material may be positioned between the plates 35 and was shown in Figure 7, so as to be coextensive with the window portion 4| and form an inner' sup port or spool 'for the conductors of the coil 42. This enables the antennastructure to be easily fabricated by first securing the plates 35, 35 and 43 together by. an adhesive or otherwise and then winding the conductor of thecoil 42 between the plates 35 and 36. As shown in Figure 8, a similar spool may be formed by employing a ring 44 preferably of transparent material and positioned interiorly of the antenna coil 42, The ring 44 may. extend completely around the periphery of the window portion, but as shown in Figure 9.the inner support need not be a coniplete ring but may comprise a plurality of segments 45 of any desired shape. Figure 9 also illustrates a suitable arrangement for enabling thefiexible connector leading from the antenna to the set to be detachably connected to the antenna. For example, a pair of pin jacks 45 for receiving suitable pins connected to the conductors in the flexible connector may be secured to the antenna structure and connected to the coil 42.

By employing properly formed plates 46 having peripheral recesses 48 as shown in Figure 1 0, aninner transparent support or spoolportion 49 may be provided for the antenna coil. Two plates only are required for this construction. Figure 10 also illustrates the antenna adhesively secured to the surface of a window pane 4-1 to provide a permanent installation. The conductors of the coil 42 may be completely embedded in a single plate 50 of transparent material as shown in Figure 11 by casting or molding such material around a previously formed coil. It is apparent that any of the structures disclosed. in Figures '7 to 11 may also be provided with the at: taching means illustrated in Figures 1 to 6 for quickly attaching the antenna structure to a supporting surface or detaching the antenna from such surface, or that the attaching. means of Figures 1 to. '7 maybe omitted and the antenna structure permanently attached by an adhesive or otherwise to a supporting structure as illustrated in Figure 10. I

In, the structure of Figure 5, it is apparent that the window portions 4| of the plates supporting the coil 42 may be cut out soas to 'decrease the weight of the antenna structure and also to further decrease inpairment of vision through the antenna structure. Anantenna structure having the center portion omitted is shown in Figure 12 and may comprise plates 5! havinga central opening 52 coextensive withthe opening in the coil 42. The coil 42 may be positioned between the. plates 5| and secured :by adhesives or otherwise. "As shown .in Figure 13, a rirg. 53 may be employed as a supportifor the coil 42 and also to provide more efficient means for securing the plates 54 together. Also-,as shown in Figure 14, plates 55 having peripheral recesses56 and openings 51 therethrough may be employed to provide a support for the coil in a manner. similar. to that shownin Figure 10. Furthermore, a flat tubular structure of insulating material 58 enclosing the coil 42 may be employed to support the coil. Such a tube may be fabricated about a preformed coil, for example,

by molding plastic material therearound orfby wrapping the coil withanlimpregnated tape and solidifying the same, for example by dryingor with heat and pressure. 7 When the center-portion of the antenna struc ture-is thus removed, itis further ,apparentthat the plates tor other supporting" structure may even be made or translucent or opaque insulating 'material without seriously im'peding vision through the antenna, as the coil 42' is itself opaque. Furthermore, if the antenna structures of Figures 12 to. 15- are to'be permanently secured in a desired position, "the vacuum cups of either the structures of Figure l or Figure-5 with their associated supporting/members may be omitted and'the remaining. antenna structure adhesively or otherwise permanently at tached toa supporting surface in a manner-similar to that described with reference to- Figures 7 to 11.; Thus, antenna structures having transparent center portions orcut outcenter portions may be glued to glassof an automobile window or windshield, or similar closure for openingsin other shielding structures.

Also, it is possible to incorporatethecoil of the antenna. between the layers of laminated glasses such as so-called 'safety glass. For example, the coil of theantenna can be mounted between the glass laminations of the ventilating door window-employed in many automobiles, other door windows, windshield or rear window o-fan automobile. The coil may-occupy a corner or end of a windowo-r windshield ormay extend around the periphery thereof. Sim-ilar structures may be employed for windo'ws'in boats, airplanes, buildings, etc. An exampleof such a structure is illustrated in Figure 16,.in which a pane of laminated glass is shown with an antenna coil 59 positioned therein preferably between the glass laminations. The glass :58 may be employed as a window closure in a shielding or other structure and the coil of detachableconnector, for example the pin jacks'of Figure 9, may: be secured to the glass 58 or the support for the glass so that a connecting element carried: by the radio set may serve todetachably conn'ectthe set to the antenna coil 59, In allof thestructures described, a rigid antenna pane1 structure is provided such that variations in reception are not caused by relative movementbetween portions of the antenna structure, and'obstruction of vision is minimized.

As indicated above, the transparentmaterial forming a support for the conductor of the antenna may be relatively thin plates of glass between which the conductors are secured] For antennas which are intended to bemove'd from place to place, it is preferable to form the trans parent plates of less frangible material such as any of the transparent plastics nowavailable commercially. For example, transparent" sheets of synthetic resins such as phenolic condensa tion or similar condensation products may be employed. Also, sheets of various cellulose derivatives; or regenerated cellulose, for example, cellulose acetate, are suitable. "Various other materials having similar properties may be" employed; also described above, instead or employing a-s-heet of; supporting material upon each side of the antenna --'coi-l'-,"'-the conductors of the coil may-be embeddedin the body or-surface of a single plate of transparent insulating-material, for example, by first forming 'an;antenna coil and then molding or casting the insulating ma terial about the coil so that, the conductorsare positioned entirely within the body; of .the. in'- sulating material or aresufiiciently embedded in the surface to be rigidly held in position. If either the separate plates of insulating material with the conductors positioned between the plates or an integral structure, .withthe. conductors embedded in a single panel of material is employed, the-supporting material ion/the coils should be of-suificient thickness to provide arelatively rigid panel structure, particularly when suction cup or similar attaching means are secured to thesupporting material in a manner similar-to that shown in the drawings. .When the center portion of the supporting material is omitted as in Figures 12 to 15,.it is apparent that supporting materials similar to those discussed above can be employed either as separate plates'or with the conductors embedded in a single plate, but'that the supporting materialneed not necessarily be transparent. -When the supporting structure is, thus, not required to be transparent, less expensive materials such fiber board. or impregnated paper or cardboard can be satisfactorily employed. In general, the

supporting material should be an insulator and In Figures 17 and 18,. one suitable :means is shown for combining an antenna structure such as those shown in Figuresl to 6 with a portable radio receiver. In accordance with these figures, a compartment 6| provided with a closure such as a door 62 is positioned in one end of the casing 63..of the radioset. The casing 63 may also provide a compartment 64 for the set chassis (not shown) and acompartment ,65 for a battery (not shown). The door 62, shownin Figure 18, is not shown in Figure 17 in order to more clearly illustrate the disposition of the antenna in the compartment 6|. i i

Many portable receivers are provided with a circuit enabling the set to also be plugged in to a power line for operation therefrom in order to conserve the batteries. The compartment 6| mayalso serve as a convenient storage place for the flexible connector 66 for connecting the set to a power line. That is to say, the connector 66 may be coiled upon brackets 61 secured to the realwall 68 of the compartment when not invuse. The'flexible connector 30 for the antenna structure may be folded or wound around the an tennastructure l0 and the entire antenna structure inserted within the compartment 6! as shown in Figure 17 andin dotted lines in Figure 18. A notch (not shown) may be provided, in an edge of the door or other closure to enable the conductor 66 to extend exteriorly of the compartment 6|- when the closure is in closedposition.

During normal operation of, the set a built-in antenna .69 may be connected tothe set through the normally closed contactslll of the jack 33 .and conductors 1|. When it is desired to employ the antenna |B,.ior example, when the set is positioned within a shielding structure, the antenna) may be removed from the compartment 6| and positioned adjacent an opening in the shielding structure. The plug 32 attached to the flexibleconnector may be inserted" within "the jack- 33 to open the contacts l0 and at the sametime completea connection between the conductors H and the flexible conductors 28 and 29 of the fiexible'connector 30. It will thus be seen that I have provided a radio set which is not only operative by reason of a built-in antenna, but a receiver which may be rendered operative when positioned within a shielding structure by employing an auxiliary antenna struc ture which may be positioned in an opening in the shielding structure and which does not materially obstruct vision through such opening. It is also possible to omit the. built-in antenna and employ the removable antenna for normal operation of the set by permanently connecting the removable antenna to the set so that signal energy is deliveredto the set by the removable antenna when, positioned in its compartment in the set casing.

This application is a division of my co-pending application Serial No, 298,302 filed October 6, 1939, now Patent 2,250,387 granted July 22, 1941.

While I have disclosed the preferred embodiments of my invention, it is understood that the details thereof may be. varied within the scope of the following claims;

. I claim:

l. A radio antenna for enhancing radio reception by a receiver positioned within a shielding structure of electrically conducting .material having an opening of predetermined area therein, said antenna comprising a conductor forming a loop having an area enclosed thereby which is substantially smaller than half of the area of said opening, means for supporting said loop substantially in the plane of said opening and substantially oil center with respect to the center of said opening-and means for transferring radio energy from said loop to said receiver. 2. A radio antenna for enhancing radio reception by a receiver positioned within a shielding structure of electrically conducting material having an opening of substantial'area therein, comprising a panel of insulating material arranged to close said opening, a conductor forming a loop whose enclosed area is substantially less than one half the area of said opening, means for supporting said loop by said panel of insulating material in a position substantially off center with respect to the center of said.opening, and means for transferring radio energy from said loopto said receiver.

3. A radio antenna for enhancing radio reception by a receiver positioned within a shielding structure of electrically conducting material having an opening of substantial area therein, comprising a transparent panel of insulating material arranged to close said opening, a conductor forming a loop whose enclosed area is substantially less than half the area of said opening, means for supporting said loop by said panel in a position 01f center with respect to the center of said opening; and means for transferring radio energy, from said loop to said receiver.

- EUGENE F. MCDONALD, JR. 

